Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759254AbZJHSE5 (ORCPT ); Thu, 8 Oct 2009 14:04:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759123AbZJHSE4 (ORCPT ); Thu, 8 Oct 2009 14:04:56 -0400 Received: from smtp2.ultrahosting.com ([74.213.174.253]:52428 "EHLO smtp.ultrahosting.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752245AbZJHSEz (ORCPT ); Thu, 8 Oct 2009 14:04:55 -0400 Date: Thu, 8 Oct 2009 13:57:53 -0400 (EDT) From: Christoph Lameter X-X-Sender: cl@gentwo.org To: Rusty Russell cc: Ingo Molnar , akpm@linux-foundation.org, linux-kernel@vger.kernel.org, David Howells , Tejun Heo , Eric Dumazet , Pekka Enberg Subject: [Patchs vs. percpu-next] Use this_cpu_xx to dynamically allocate counters In-Reply-To: <200910062034.40864.rusty@rustcorp.com.au> Message-ID: References: <20091001212521.123389189@gentwo.org> <20091002093453.GA21427@elte.hu> <200910062034.40864.rusty@rustcorp.com.au> User-Agent: Alpine 1.10 (DEB 962 2008-03-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6704 Lines: 210 On Tue, 6 Oct 2009, Rusty Russell wrote: > Does this mean we can kill local.h soon? Can we remove local.h from modules? Subject: Module handling: Use this_cpu_xx to dynamically allocate counters Use cpu ops to deal with the per cpu data instead of a local_t. Reduces memory requirements, cache footprint and decreases cycle counts. The this_cpu_xx operations are also used for !SMP mode. Otherwise we could not drop the use of __module_ref_addr() which would make per cpu data handling complicated. this_cpu_xx operations have their own fallback for !SMP. Signed-off-by: Christoph Lameter --- include/linux/module.h | 36 ++++++++++++------------------------ kernel/module.c | 30 ++++++++++++++++-------------- kernel/trace/ring_buffer.c | 1 + 3 files changed, 29 insertions(+), 38 deletions(-) Index: linux-2.6/include/linux/module.h =================================================================== --- linux-2.6.orig/include/linux/module.h 2009-10-08 11:36:05.000000000 -0500 +++ linux-2.6/include/linux/module.h 2009-10-08 11:40:57.000000000 -0500 @@ -16,8 +16,7 @@ #include #include #include - -#include +#include #include #include @@ -361,11 +360,9 @@ struct module /* Destruction function. */ void (*exit)(void); -#ifdef CONFIG_SMP - char *refptr; -#else - local_t ref; -#endif + struct module_ref { + int count; + } *refptr; #endif #ifdef CONFIG_CONSTRUCTORS @@ -452,25 +449,16 @@ void __symbol_put(const char *symbol); #define symbol_put(x) __symbol_put(MODULE_SYMBOL_PREFIX #x) void symbol_put_addr(void *addr); -static inline local_t *__module_ref_addr(struct module *mod, int cpu) -{ -#ifdef CONFIG_SMP - return (local_t *) (mod->refptr + per_cpu_offset(cpu)); -#else - return &mod->ref; -#endif -} - /* Sometimes we know we already have a refcount, and it's easier not to handle the error case (which only happens with rmmod --wait). */ static inline void __module_get(struct module *module) { if (module) { - unsigned int cpu = get_cpu(); - local_inc(__module_ref_addr(module, cpu)); + preempt_disable(); + __this_cpu_inc(module->refptr->count); trace_module_get(module, _THIS_IP_, - local_read(__module_ref_addr(module, cpu))); - put_cpu(); + __this_cpu_read(module->refptr->count)); + preempt_enable(); } } @@ -479,15 +467,15 @@ static inline int try_module_get(struct int ret = 1; if (module) { - unsigned int cpu = get_cpu(); if (likely(module_is_live(module))) { - local_inc(__module_ref_addr(module, cpu)); + preempt_disable(); + __this_cpu_inc(module->refptr->count); trace_module_get(module, _THIS_IP_, - local_read(__module_ref_addr(module, cpu))); + __this_cpu_read(module->refptr->count)); + preempt_enable(); } else ret = 0; - put_cpu(); } return ret; } Index: linux-2.6/kernel/module.c =================================================================== --- linux-2.6.orig/kernel/module.c 2009-10-08 11:36:05.000000000 -0500 +++ linux-2.6/kernel/module.c 2009-10-08 11:42:05.000000000 -0500 @@ -474,9 +474,10 @@ static void module_unload_init(struct mo INIT_LIST_HEAD(&mod->modules_which_use_me); for_each_possible_cpu(cpu) - local_set(__module_ref_addr(mod, cpu), 0); + per_cpu_ptr(mod->refptr, cpu)->count = 0; + /* Hold reference count during initialization. */ - local_set(__module_ref_addr(mod, raw_smp_processor_id()), 1); + __this_cpu_write(mod->refptr->count, 1); /* Backwards compatibility macros put refcount during init. */ mod->waiter = current; } @@ -555,6 +556,7 @@ static void module_unload_free(struct mo kfree(use); sysfs_remove_link(i->holders_dir, mod->name); /* There can be at most one match. */ + free_percpu(i->refptr); break; } } @@ -619,7 +621,7 @@ unsigned int module_refcount(struct modu int cpu; for_each_possible_cpu(cpu) - total += local_read(__module_ref_addr(mod, cpu)); + total += per_cpu_ptr(mod->refptr, cpu)->count; return total; } EXPORT_SYMBOL(module_refcount); @@ -796,14 +798,15 @@ static struct module_attribute refcnt = void module_put(struct module *module) { if (module) { - unsigned int cpu = get_cpu(); - local_dec(__module_ref_addr(module, cpu)); + preempt_disable(); + __this_cpu_dec(module->refptr->count); + trace_module_put(module, _RET_IP_, - local_read(__module_ref_addr(module, cpu))); + __this_cpu_read(module->refptr->count)); /* Maybe they're waiting for us to drop reference? */ if (unlikely(!module_is_live(module))) wake_up_process(module->waiter); - put_cpu(); + preempt_enable(); } } EXPORT_SYMBOL(module_put); @@ -1377,9 +1380,9 @@ static void free_module(struct module *m kfree(mod->args); if (mod->percpu) percpu_modfree(mod->percpu); -#if defined(CONFIG_MODULE_UNLOAD) && defined(CONFIG_SMP) +#if defined(CONFIG_MODULE_UNLOAD) if (mod->refptr) - percpu_modfree(mod->refptr); + free_percpu(mod->refptr); #endif /* Free lock-classes: */ lockdep_free_key_range(mod->module_core, mod->core_size); @@ -2145,9 +2148,8 @@ static noinline struct module *load_modu mod = (void *)sechdrs[modindex].sh_addr; kmemleak_load_module(mod, hdr, sechdrs, secstrings); -#if defined(CONFIG_MODULE_UNLOAD) && defined(CONFIG_SMP) - mod->refptr = percpu_modalloc(sizeof(local_t), __alignof__(local_t), - mod->name); +#if defined(CONFIG_MODULE_UNLOAD) + mod->refptr = alloc_percpu(struct module_ref); if (!mod->refptr) { err = -ENOMEM; goto free_init; @@ -2373,8 +2375,8 @@ static noinline struct module *load_modu kobject_put(&mod->mkobj.kobj); free_unload: module_unload_free(mod); -#if defined(CONFIG_MODULE_UNLOAD) && defined(CONFIG_SMP) - percpu_modfree(mod->refptr); +#if defined(CONFIG_MODULE_UNLOAD) + free_percpu(mod->refptr); free_init: #endif module_free(mod, mod->module_init); Index: linux-2.6/kernel/trace/ring_buffer.c =================================================================== --- linux-2.6.orig/kernel/trace/ring_buffer.c 2009-10-08 12:46:29.000000000 -0500 +++ linux-2.6/kernel/trace/ring_buffer.c 2009-10-08 12:46:46.000000000 -0500 @@ -12,6 +12,7 @@ #include #include #include +#include #include #include #include -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/